The present invention relates to a spark erosion machine having coaxially spaced, forcibly coupled, pivotable wire guidance heads for guiding a wire-type electrode in the erosion zone of the spark erosion machine.
Such a spark erosion machine is generally known from DE-OS No. 32 01 544. In order to make conical or other sloping cuts in wire erosion machines, the wire electrode must be inclined. In order to obtain a satisfactory entry and exit of the electrode with respect to the wire guidance heads, it is desirable to align the axes of the heads in line with the wire electrode guided between the heads. The wire guidance heads must therefore be coaxial to one another. To solve this problem, DE-OS No. 32 01 544 proposes to forcibly couple together the two wire guidance heads by means of a parallelogram linkage. A separate parallelogram linkage is associated with each wire guidance head, the two parallelogram linkages being connected by a common vertical spindle, which is also telescopically extendible. The spindle is positioned parallel to the wire electrode portion guided between the wire guidance heads and, through the operation of the two parallelogram linkages fixed thereto, achieves the coaxial alignment of the guidance heads.
It is a disadvantage of this arrangement that the vertical spindle can only have a limited spacing from the electrode, corresponding to the length of the parallelogram linkages. However, this limits the operating range of the spark erosion machine, so that it is unsuitable for larger workpieces. If the parallelogram linkage is made very large, it is subject to thermal expansion, dimensional inaccuracies and tolerances, so that the axial alignment of the wire guidance heads suffers.